Combination sensing means and multistage vibrating valve mechanism



y 8, 1962 G. A. LOVEALL. JR 3,033,299

COMBINATION SENSING MEANS AND MULTI-STAGE VIBRATING VALVE MECHANISM 2 Sheets-Sheet 1 Filed Dec. 7, 1959 Witness M y 1962 G. A. LOVEALL. JR 3,033,299

COMBINATION SENSING MEANS AND MULTL-STAGE VIBRATING VALVE MECHANISM Filed Dec. 7, 1959 2 Sheets-Sheet 2 b lj 24 J J x F O Wihmss 2 w V r y rates Unite My invention relates to valve mechanisms and more particularly to a valve mechanism that can responsively provide a vibrating motion to its various parts at diflerent points between its extreme open and closed positions.

In many areas of modern industry, the cost of goods is greatly affected by the expense of material handling. Material handling is itself a vital component of any production enterprise and is especially important because it influences speed of production as well as quality control through accuracy in material measurements. Accuracy in measuring material is particularly vital in those industries which handle ore, concrete components, grain and the like. For example, the ready-mix concrete industry must provide charging equipment that will accurately deliver the proper components of concrete to the awaiting truck-mounted concrete mixers. The same is true for those related industries which produce concrete products such as building blocks or the like.

The concrete industry often provides separate overhead bins which contain various ingredients. The separate ingredients are selectively permitted to pass from the bin through a valve mechanism of some description to be weighed and then mixed or otherwise used. This general physical arrangement is commonplace in many other industries as well. But whatever the material being han dled, all industries are confronted with the problem of controlling the flow of material from the overhead bin through the valve mechanism. Usually, the material flows through a constricted valve opening from the effects of gravity. Sometimes the material will flow through the valve in a uniform manner as water would be expected to move. However, many times the material, because of its non-homogeneous composition, will flow intermittently and erratically through the open valve. In other cases, the material will bridge or arch over the valve opening and then suddenly gush through the valve before the valve control means, if any, can sense the excessive onrush of material. Obviously, all of these factors, separately or together, impair the control of the valve over the material flow. These problems are often compounded by the fact that even different bin loads of similar material may react differently upon moving through the valve because of moisture conditions or the like.

Therefore, the principal object of my invention is to provide a combination sensing means and multi-stage vibrating valve mechanism that can accurately control the flow of material through the valve despite the composition of the material.

A further object of my invention is to provide a combination sensing means and multi-stage vibrating valve mechanism which will automatically respond to variations in flow of material through the valve.

A still further object of my invention is to provide a combination sensing means and multistage vibrating Valve mechanism that can overcome the bridging action of material above the valve.

A still further object of my invention is to provide a combination sensing means and multi-stage vibrating valve mechanism that can have its vibrating components selectively adjusted to operate at any desired position in their operational range so as to be adaptable to handling different kinds of materials.

A still further object of my invention is to provide atent a combination sensing means and multi-stage vibrating valve mechanism that is economical of manufacture, durable in use and refined in appearance.

These and other objects will be apparent to those skilled in the art.

My invention consists in the construction, arrangements, and combination, of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in my claims, and illustrated in the accompanying drawings, in which:

PEG. 1 is a perspective view of my valve mechanism showing primarily the structure whereby the valve is opened and closed;

FIG. 2 is a perspective view of the rotary gate in my valve;

FIG. 3 is a sectional view of my valve taken on line 33 of FIG. 1;

FIG. 4- is an elevational view of my valve taken on the side of the valve opposite to the double acting air cylinder shown in FIG. 1

FIG. 5 is a schematic view of the scale beam in relation to the beam switches when the scale is loaded and balanced;

FIG. 6 is a schematic View of the scale beam in relation to the beam switches when the scale is partially loaded and my valve is operating in one position of its operating range;

FIG. 7 is a schematic view of the scale beam in relation to the beam switches when the scale beam in its unloaded and underweight position and my valve is closed;

FIG. 8 is a wiring diagram of my device before the operation cycle begins when the scale beam is in its underweight position, the control switch is open and the valve is closed;

FIG. 9 is a wiring diagram of my device when the operational cycle has begun and the valve is being vibrated in one of its open positions;

FIG. 10 is a wiring diagram of my device when the scale beam has allowed one of the beam switches to open to interrupt the first vibration sequence of the valve;

FIG. 11 is a wiring diagram of my device when the valve is being vibrated in a second open position;

FIG. 12 i a wiring diagram of my device when the scale beam is "balanced and the valve is closed; and

FIG. 13 is an elevational view of my device installed under an overhead bin unit.

With reference to FIG. 13, l have used the numerals it to designate column members which can support overhead bin 12. Valve 14 is mounted in a manner to be described on the bottom of bin 12. A scale means 16 with a bin 13 is also supported in any conventional fashion by the basic structure represented by the columns 10. A scale beam 20 is pivotally mounted on scale means 16 in the usual manner. Micro beam switches 22 and 24 are mounted on scale means 16 in any convenient manner and are located in the path of scale beam 20 to be actuated thereby in a manner to be described hereafter. Micro beam switches 22 and 24 are of conventional construction and have typical spring loaded plungers which normally hold the switches in an open position.

Valve 14 has a rectangular container 26 which has at least a horizontal flange 28 around its upper edge. Flange 28 can be secured to a corresponding flange 30 which extends around the open bottom of bin 12 by bolt and nut elements 32 which extend through registering holes in the respective flanges.

Baffle plates 34 extend downwardly and inwardly from the flange 30 on opposite sides of container 26 and are secured to the container by welding or the like. The

lower edges of plates 34 terminate in spaced relation as shown in FIG. 3. A shaft 36 extends through the lower portion of container 26 and is rotatably mounted therein. The shaft 36 is located below the lower edges of baffle plates 34 and is parallel therewith. As shown in FIGS. 1 and 4, the opposite ends of shaft 36 protrude beyond the exterior walls of container 26. Arms 38 are welded to shaft 36 and extend radially therefrom. A curved plate or gate 46 is welded to the outer ends of arms 38. The curvature of gate 46 along with the length of arms 38 is such that the rotation of shaft 36 will permit the gate to close the space between the lower edges of baffle plates 34 but will also permit the gate to rotate to a position away from the plates. In this manner, the space between the plates can be selectively opened and closed by the subsequent rotation of shaft 36 in alternate directions.

A bracket 42 is bolted or otherwise secured to container 26 and extends outwardly from one side thereof. A horizontal double acting air cylinder 44 is pivotally connected by one of its ends to bracket 42 by means of hinge element 46. A piston rod 48 extends from the end of cylinder 44 over and above shaft 36 and is pivotally connected to the shaft 36 by link 56..

Air lines 51 and 52 extend from opposite ends of cylinder 44 in conventional fashion and have their opposite ends secured to air valve 54. Air valve 54 is secured in any convenient manner to bracket 42. A source of compressed air is brought into valve 54 by air line 55 Valve 54 is of conventional design and is controlled by a spring loaded electrical solenoid 56. When the solehold 56 is in its normal, unexcited position, it will hold the piston (not shown) in the valve in a position where air will be communicated from air line 55 to line 52. This causes the flow of air to force the piston rod 48 out of cylinder 44 and rotates shaft 36 to permit gate 40 to close the gap between bathe plates 34. When the solenoid 56 is electrically excited, the piston in the air valve 54 will be withdrawn to a second position to exhaust air from line 52 and connect lines '5 and 51 to reverse the direction of movement of the piston rod 48 within cylinder 44. This action causes piston rod 48 to rotate shaft 36 in an opposite direction to move gate 40 away from baffle plates 84 so that the valve 14 can be opened. An electrical connection box 58 is secured to solenoid 56 in any convenient manner as shown in.

FIG. 4.

The protruding end of shaft 36 opposite to the end of the shaft which is connected to piston rod 48 has cam discs .68 and 62 secured thereon by set screws or the like so that their rotational positions on the shaft can be selectively adjusted. Disc 60 has a portion 64 of reduced radius and a portion 66 of increased radius with cam shoulders 67 and 68 therebetween. Disc 62 has a portion 78 of reduced radius and a portion 72 of increased radius with cam shoulders 74 therebetween.

Micro switches or gate switches 76 and 7 8 are mounted in any convenient fashion to container 26 on opposite sides of cam discs 66 and 62. A compound linkage member 80 with a wheel 82 rotatably mounted on its protruding free end is operatively secured in any convenient manner to the conventional plunger on gate switch 76. Wheel 82 movably engages cam disc 60 and the gate switch 76 is normally closed when the wheel engages the portion 64 of reduced radius on the disc 60. However, engagement of the wheel 82 with the cam shoulder 68 or portion 66 of increased radius on disc 60 will open the gate switch 76. Similarly, compound linkage member 84 with wheel 86 rotatably mounted on its protruding free end is operatively secured in any convenient manner to the conventional plunger on gate switch 78. Wheel 86 movably engages cam disc 62 and the gate switch 78 is normally closed when the wheel engages the portion 76 of reduced radius on disc 62. However, engagement of the wheel 86 with the cam 4- shouldcr 74 or portion 72 of increased radius on disc 62 will open the gate switch 78. The cam discs 60 and 62 are normally positioned on shaft 36 so that their respective cam shoulders 68 and 74 are not in alignment.

Lines 88 and 90 are connected to a source of electrical energy. A control switch 92, which is shown only schematically in FIGS. 8 to 12, is imposed in line 88 for the operators use. Line 88 connects switch 92 with beam switch 22 and line 94 connects beam switch 22 with one side of gate switch '76. Line 96 thereupon connects the other side of gate switch 76 with solenoid 56. Line 94 is connected to the other side of solenoid 56 to complete one circuit from line 88, beam switch 22, line 9 4, switch 76, line 96, solenoid 56 and line 90. A second parallel circuit is comprised of line $8 which connects line 88 and beam switch 24; line 166 which connects the other side of beam switch 24 with gate switch '78, line 162, which connects the other side of, gate switch 78 with the solenoid 56.

The normal operation of my device is as follows: It has already been pointed out that the electrical excitement of solenoid 56 will cause gate 4 to move to an open position with respect to bathe plates 45 and the collapsing of the solenoid field will cause the immediate closing of the gate. I have found that the instantaneous excitement and collapsing of the solenoid field in a rapid and continuous manner will cause the gate 48 to rapidly vibrate over a small increment of its total possible displacement. Thus, the rapid but intermittent breaking of the solenoid field will cause the gate 48 to pulsate a small increment as the cylinder 44 is continuously endeavoring to close and then open the gate. Furthermore, the gate will vibrate in this fashion at Whatever position between its open and closed conditions that the solenoid field is suddenly and intermittently interrupted.

This vibration of the gate 40 serves a very beneficial need in material handling equipment because the vibrations tend to break down or prevent any arching effect of the material above the valve. I have found that the vibration of my gate in an open or semi-open position will result in a rapid discharge of material through the valve 14, but that speed as well as accuracy is attained if the gate is allowed to vibrate subsequently at a second point nearer a closed position as the desired quantity ofi flow approaches completeness. This second vibrating action of the gate 46 is necessary because the flow of material through the valve is many times very rapid, and if the initial vibrating action took place when the gate was substantially open, the gate could not close fast enough to immediately stop the flow when the desired quantity or weight of material was delivered through the valve. Thus, I have provided a structure that can vibrate the gate in a substantially opened position; and then as the desired quantity of flow is approached, the gate will move to a second vibrating position near a full closed position so that the flow of material can be instantaneously stopped when the desired flow has been attained. Obviously, with some material and with small quantities, the two vibrating positions of the gate could be very close to each other.

Cam discs 60 and 62 can be set on shaft 36 when the gate 40 is closed. Gate switch 78 will control the first vibration phase of the gate 46 and'gate switch 76 will control the second vibration phase of thegate. Accordingly, disc 68 is positioned on shaft 36 in such a manner that the immediate clockwise rotation of shaft 36 as viewed in FIG. 4 will open the gate and move the point of engagement of the disc 68 and wheel 68 from the portion 64 of shorter radius over the shoulder 68 to the portion 66 of greater radius which will cause switch 76 to open shortly after the gate is opened. At the same time, disc 62 is positioned so that wheel 86 will not move from the portion 76 of shorter radius into engagement with cam shoulder 74 until the gate has opened to the point where the first vibrating position of the gate 46 is to take place. Thus, gate switch 78 will remain closed until the initial vibration begins and gate switch 76 will move from a closed to an open position as this first vibrating position is being attained. The positioning of the cam discs 60 and 62 on shaft 36 will determine the positions at which the gate 40 will vibrate.

Having so adjusted the cam discs 60 and 62, the operator places his scale beam 20 in a lowered underweight position as shown in FIG. 7. This action closes beam switches 22 and 24 and places my circuitry in the condition shown in FIG. 8 with both beam switches and both gate switches being closed. The operator can then close control switch 92 and thesolenoid field 56 immediately becomes excited and the gate 40 immediately starts to open in the manner described. As the gate 40 begins to open, the shaft 36 (as viewed in'FIG. 4) starts to rotate in a clockwise direction and causes wheel 82 to engage shoulder 68 and ride to an open position on disc 60 by engaging the large radius portion 66. The opening of switch 76 does not affect the solenoid 56 as it is still being energized by the circuit passing through gate switch 78. However, the continued clockwise rotational movement of gate 40 and shaft 36 causes the cam shoulder 74 on disc 62 to engage wheel 86 on gate switch 78 and switch 78 becomes opened. With both of the gate switches 76 and 78 opened, the solenoid is immediately deenergized and the gate starts to close in the manner described, thus causing an immediate reversal in motion of gate 40, shaft 36 and cam disc 62. The immediate change in motion instantly allows the wheel 86 to disengage the cam shoulder 74 on disc 62 to close gate switch 78 and the solenoid becomes alive again and starts to open the gate. Thus, the intermittent engagement of wheel 86 and cam shoulder 74 on disc 62 causes the gate 40 to vibrate back and forth a small increment as the gate switch 78 opens and closes. FIG. 9 illustrates the circuitry during this phase of the cycle.

Obviously, the vibration of the gate in the manner described above will urge the material in bin 12 to flow through the valve 14 even if the material has initially bridged over the container 26. As material begins to flow through the valve 14 and into the bin 18 which is secured to scale 16, the scale beam 20 starts to balance and moves from the position of FIG. 7 to the position in FIG. 6. By starting to assume a balanced position, beam 20 disengages the plunger of beam switch 24 and switch 24 assumes its normal open position. This places the circuitry in the condition shown in FIG. where the field of solenoid 56 is collapsed because the opening of beam switch 24 has broken the circuit intermittently held closed by the pulsating switch 78. The collapse of the field of solenoid 56 causes the gate 40 to commence to close in the manner described and the gate 40, shaft 36 and cam discs 60 and 62 thereupon rotate in a counterclockwise direction as viewed in FIG. 4. Gate switch 78 thereupon becomes closed but this does not serve to energize the solenoid since the beam switch 24, in series with gate Switch 78 remains open. However, the continued counterclockwise movement of cam disc 60 permits wheel 82 to move back over the cam shoulder 68 to close gate switch 76. The circuitry then assumes the condition shown in FIG. 11. The closing of gate switch 76 excites the solenoid 56 through the series connected switches 22 and 76. The excitement of the solenoid then causes the gate to reverse its motion and start to open, which also causes the wheel 82 to start to ride over the cam shoulder 68 on disc 60. Thus, they gate vibrates in this second position as switch 76 opens and closes upon engaging and disengaging, respectively, the cam shoulder 68. This permits the material to flow at a slower rate through the valve with the gate in a position near complete closure.

As the scale bin 18 acquires its predetermined load of material, the scale beam 26 swings into balance as shown in FIG. 5, and the plunger on beam switch 22 also becomes released and switch 22 is thereupon opened. The

circuitry thereupon assumw the condition shown in FIG. 12 where the solenoid is completely de-energized by the two open beam switches 22 and 24. The gate 40 will immediately close in the manner described and the flow of material through the valve will instantly stop.

From the foregoing it is seen that my device will permit gate vibration at various stages of the gates range of movement and will automatically sense the intervals of vibration. Obviously, additional vibration intervals of gate 40 could be implemented by using additional circuits which each utilize a cam disc gate switch and beam switch in the manner indicated. Thus, it is apparent that my invention will accomplish at least all of its stated objectives.

Some changes may be made in the construction and arrangement of my combination sensing means and multistage vibrating valve mechanism without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In a device of the class described, a container having an opening therein, a gate 'movably secured to said container and adapted to close said opening at times, a cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a power means, a power diverting means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is direvted to one end of said cylinder and will move said gate in an opposite direction when power is direvted to the other end of said cylinder, said power diverting means and said cylinder normally urging said gate to close said opening, means for selectively actuating said power diverting means to cause said cylinder to start to open said gate, a first control means connecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other after said gate has been opened a given increment, a second control means secured to said first control means to render said first control means inoperative at times, a third control means connecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other after said second control means has rendered said first control means inoperative, and a fourth control means connected to said third control means to render said third control means inoperative at times.

2. In a device of the class described, a container having an opening therein adapted to have flowable materials pass therethrough, a gate movably secured to said container and adapted to close said opening at times, a cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a power means, a power diverting means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is diverted to one end of said cylinder means and will move said gate in an opposite direction when power is diverted to the other end of said cylinder means, said power diverting means and said cylinder means normally urging said gate to close said opening, means for selectively actuating said power diverting means to cause said cylinder to start to open said gate, a measuring means connected to said container below said opening and being responsive to the quantity of material flowing through said opening, a first control means connecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other after said gate has been opened a given increment, a second control means connecting said first control means and said measuring means to render said first control means inoperative after a first predetermined quantity of material has passed through said opening, a third control means connecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other end after said first control means has been rendered inoperative, and a fourth control means connected to said third control means and said measuring means to render said third control means inoperative after a second predetermined quantity of material has passed through said opening.

3. In a device of the class described, a container having an opening therein, a gate movably secured to said container and adapted to close said opening at times, a cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a power means, a power diverting means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is diverted to one end of said cylinder and will move said gate in an opposite direction when power is diverted to the other end of said cylinder, said power diverting means and said cylinder normally urging said gate to close said opening, means for selectively actuating said power diverting means to cause said cylinder to start to open said gate, a first control means connecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other after said gate has been opened a given increment, a second control means secured to said first control means to render said first control means inoperative at times, a third control means conecting said gate and said power diverting means to intermittently divert power from one end of said cylinder to the other after said second control means has rendered said first control means inoperative,- and a fourth control means connected to said third control means to render said third control means inoperative at times; said first and third control means being adjustably connected to said gate.

4. In a device of the class described, a container having an opening therein, a gate movably secured to said container and adaptedto close said opening at times, a cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a power means, a power diverting valve means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is diverted to one end of said cylinder means andwill move said gate in an opposite direction when power is diverted to the other end of said cylinder means, an electrical solenoid meansin said valve which normally diverts power to said cylinder means to close said gate when not being electrically excited, a first switch on said container normallyin a -closed position, a first cam means secured to said gate and adapted to open said first switch when said gate is opened a predetermined increment, a second switch connected to said container and normally in a closed position, a second cam means on said gate adapted to open said second switch when said gate is opened a predetermined increment less than said first predetermined increment, a third switch electrically connected in series with said first switch, a fourth switch electrically connected in series with said second switch, said first and second switches electrically connected in parallel with said electrical solenoid in said valve, said solenoid and i said third and fourth switches electrically connected to a source of electrical energy, and a fifth switch interposed in the connection between said solenoid and said source of electrical energy. v I

5. In a device of the class described, a container having an opening therein, a gate niovably secured to said container and adapted to close said opening at times, a

cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a 7

said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is diverted to one end of said cylinder means and will move said gate in an opposite direction when power is diverted to the other end of said cylinder means, an electrical solenoid means in said valve which normally diverts power to said cylinder means to close said gate when not being electrically excited, a first switch on said container normally in a closed position, a first cam means adjustably secured to said gate and adapted to open said first switch when said gate is opened a predetermined increment, a second switch connected to said container and normally in a closed position, a second cam means on said gate adapted to open said second switch when said gate is opened a predetermined increment less than said first predetermined increment, a third switch electrically connected in series with said first switch, a fourth switch electrically connected in series with said second switch, said first and second switches electrically connected in parallel with said electrical solenoid in said valve, said solenoid and said third and fourth switches electrically connected to a source of electrical energy, and a fifth switch interposed in the connection between said solenoid and said source of electrical energy.

6. In a device of the class described, a container having an opening therein, a gate movably secured to said container and adapted to close said opening at times, a cylinder means secured to said container and operatively connected to said gate to reciprocate said gate at times, a power means, a power diverting valve means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will move said gate in one direction when power is diverted to one end of said cylinder means and will move said gate in an opposite direction when power is diverted to the other end of said cylinder means, an electrical solenoid means in said valve which normally diverts power to said cylinder means to close said gate when not being electrically excited, at first switch on said container normally in a closed position, a first cam means secured to said gate and adapted to open said first switch when said gate is opened a predetermined increment, a second switch connected to said container and normally in a closed position, a second cam means on said gate adapted to open said secand switch when said gate is opened a predetermined increment less than said first predetermined increment, a measuring means connected to said container below said opening and being responsive to the quantity of material flowing through said opening, a first control means connecting said measuring means and said first switch to prevent the fiow or" electricity to said first switch after a first predetermined quantity of material has passed through said opening, a second control means connecting said measuring means and said second switch to prevent the flow of electricity to said second switch after a second predetermined quantityof material has passed through said opening, said first and second switches electrically connected in parallel with said electrical solenoid in said valve, said solenoid and said first and second switches electrically connected to a source of electrical energy,

opening at times upon rotational movement of said'shaft in one direction, a cylinder means secured to said container and operatively connected to'said shaft to rotate said shaft'in alternating directions at times, a power means, a power diverting valve'means connecting said power means with opposite ends of said cylinder means cylinder and will rotate said shaft in an opposite direction when power is diverted to the other end of said cylinder, an electrical solenoid means in said power diverting valve means which, normally diverts power to said cylinder means to rotate said shaft and hence said gate to close said opening in said container, a first switch on said container normally in a closed condition, a first cam means on said shaft and adapted to open said first switch when said gate is opened a predetermined increment, a second switch connected to said container and normally in a closed position, a second carn means on said shaft adapted to open said second switch when said gate is opened a predetermined increment less than said first predetermined increment, a third switch electrically connected in series with said first switch, a fourth switch electrically connected in series with said second switch, said first and second switches electrically connected in parallel with said electrical solenoid in said valve, said solenoid and said third and fourth switches electrically connected to a source of electrical energy, and a fifth switch interposed in the connection between said solenoid and said source of electrical energy.

8. In a device of the class described, a container having an opening therein, a shaft rotatably mounted on said container in the close proximity of said opening, a gate movably secured to said shaft and adapted to close said opening at times upon rotational movement of said shaft in one direction, a cylinder means secured to said container and operatively connected to said shaft to rotate said shaft in alternating directions at times, a power means, a power diverting valve means connecting said power means with opposite ends of said cylinder means whereby said cylinder means will rotate said shaft in one direction when power is diverted toward one end of said cylinder and will rotate said shaft in an opposite direction when power is diverted to the other end of said cylinder, an electrical solenoid means in said power diverting valve means which normally diverts power to said cylinder means to rotate said shaft and hence said gate to close said opening in said container, a first switch on said container normally in a closed condition, a first cam means on said shaft and adapted to open said first switch when said gate is opened a predetermined increment, a second switch connected to said container and normally in a closed position, a second cam means on said shaft adapted to open said second switch when said gate is opened a predetermined increment less than said first predetermined increment, a third switch electrically connected in series with said first switch, a fourth switch electrically connected in series with said second switch, said first and second switches electrically connected in parallel with said electrical solenoid in said valve, said solenoid and said third and fourth switches electrically connected to a source of electrical energy, a fifth switch interposed in the connection between said solenoid and said source of electrical energy, and means for adjusting the relative positions of said first and second cam means on said shaft to vary the intervals at which the respective cam means actuate said first and second switches.

References Cited in the file of this patent UNITED STATES PATENTS 928,858 Doud July 20, 1909 2,346,882 Vredenburg Apr. 18, 1944 2,634,084 McWaters Apr. 7, 1953 FOREIGN PATENTS 220,346 Australia .l Aug. 22, 1957 

